1. Field of the Invention:
This invention relates to a protective gasket with a tubular shape and a length predetermined for fitting the geometric variations of its fastening frame.
2. Description of the Related Art:
These gaskets are encountered each time that it is desired to assure sealing between a closing panel and the frame of an opening, particularly on a motor vehicle at the doors, the trunk, etc. but also on electric appliances, such as dishwashers, refrigerators, etc.
Known gaskets generally have a U-shaped clip, having a metal reinforcement, which provides a gripping effect for the gasket. The clip is covered with an elastomer of plastic, deposited by coextrusion.
Inner lips of the clip provide the sealing on the frame. The gasket itself consists of a tube, generally made of cellular rubber. Most often it is continuously formed by coextrusion and covulcanization while connected to the clip.
The frame on which the gasket is most often mounted has corners or fillets, curves and changes of planes. All of these geometric variations have the consequence of tensioning or compressing the gasket. The gasket is consequently deformed, the defects thus created destroying the quality of sealing.
To avoid these deformations in the gasket across small radius curves, several techniques are presently used:
(1) Placing a strip of sponge rubber or polyurethane foam in the tube or the tubular profile of the gasket;
(2) Injecting into the tube a special foam which expands at ambient temperature or with an addition of heat;
(3) Molding a rubber or thermoplastic elastomer in the deformed zones of the gasket to obtain a shape that perfectly fits the volume to be filled; or
(4) Using a continuous extrusion process that causes the shape of the profile to vary by increasing or reducing the thickness of the tube.
All of these processes have a major drawback: they harden the gasket and thereby increase the force necessary for closing the panel. Moreover, they entail a significant increase in cost, either because they necessitate an additional operation with a higher cost, or because they force the extrusion speed of the gasket to be reduced.